Transcriptomic profiling of induced steatosis in human and mouse precision-cut liver slices.

There is a high need for predictive human ex vivo models for non-alcoholic fatty liver disease (NAFLD). About a decade ago, precision-cut liver slices (PCLSs) have been established as an ex vivo assay for humans and other organisms. In the present study, we use transcriptomics by RNASeq to profile a new human and mouse PCLSs based assay for steatosis in NAFLD. Steatosis as quantified by an increase of triglycerides after 48 h in culture, is induced by incremental supplementation of sugars (glucose and fructose), insulin, and fatty acids (palmitate, oleate). We mirrored the experimental design for human vs. mouse liver organ derived PCLSs and profiled each organ at eight different nutrient conditions after 24 h and 48 h time in culture. Thus, the provided data allows a comprehensive analysis of the donor, species, time, and nutrient factor specific regulation of gene expression in steatosis, despite the heterogeneity of the human tissue samples. Exemplified this is demonstrated by ranking homologous gene pairs by convergent or divergent expression pattern across nutrient conditions.

The Effects of Butyrate on Induced Metabolic-Associated Fatty Liver Disease in Precision-Cut Liver Slices.

Metabolic-associated fatty liver disease (MAFLD) starts with hepatic triglyceride accumulation (steatosis) and can progress to more severe stages such as non-alcoholic steatohepatitis (NASH) and even cirrhosis. Butyrate, and butyrate-producing bacteria, have been suggested to reduce liver steatosis directly and systemically by increasing liver ß-oxidation. This study aimed to examine the influence of butyrate directly on the liver in an ex vivo induced MAFLD model. To maintain essential intercellular interactions, precision-cut liver slices (PCLSs) were used. These PCLSs were prepared from male C57BL/6J mice and cultured in varying concentrations of fructose, insulin, palmitic acid and oleic acid, to mimic metabolic syndrome. Dose-dependent triglyceride accumulation was measured after 24 and 48 h of incubation with the different medium compositions. PCLSs viability, as indicated by ATP content, was not affected by medium composition or the butyrate concentration used. Under induced steatotic conditions, butyrate did not prevent triglyceride accumulation. Moreover, it lowered the expression of genes encoding for fatty acid oxidation and only increased C4 related carnitines, which indicate butyrate oxidation. Nevertheless, butyrate lowered the fibrotic response of PCLSs, as shown by reduced gene expression of fibronectin, alpha-smooth muscle actin and osteopontin, and protein levels of type I collagen. These results suggest that in the liver, butyrate alone does not increase lipid ß-oxidation directly but might aid in the prevention of MAFLD progression to NASH and cirrhosis.

pH-dependent ileocolonic drug delivery, part I: in vitro and clinical evaluation of novel systems.

After the pH dependency of novel pH-dependent ileocolonic drug delivery systems is confirmed in vitro, their performance should be evaluated in human volunteers.

A Pathophysiological Model of Non-Alcoholic Fatty Liver Disease Using Precision-Cut Liver Slices.

Non-alcoholic fatty liver disease (NAFLD) is a common liver disorder closely related to metabolic syndrome. NAFLD can progress to an inflammatory state called non-alcoholic steatohepatitis (NASH), which may result in the development of fibrosis and hepatocellular carcinoma. To develop therapeutic strategies against NAFLD, a better understanding of the molecular mechanism is needed. Current in vitro NAFLD models fail to capture the essential interactions between liver cell types and often do not reflect the pathophysiological status of patients. To overcome limitations of commonly used in vitro and in vivo models, precision-cut liver slices (PCLSs) were used in this study. PCLSs, prepared from liver tissue obtained from male Wistar rats, were cultured in supraphysiological concentrations of glucose, fructose, insulin, and palmitic acid to mimic metabolic syndrome. Accumulation of lipid droplets was visible and measurable after 24 h in PCLSs incubated with glucose, fructose, and insulin, both in the presence and absence of palmitic acid. Upregulation of acetyl-CoA carboxylase 1 and 2, and of sterol responsive element binding protein 1c, suggests increased de novo lipogenesis in PCLSs cultured under these conditions. Additionally, carnitine palmitoyltransferase 1 expression was reduced, which indicates impaired fatty acid transport and disrupted mitochondrial ß-oxidation. Thus, steatosis was successfully induced in PCLSs with modified culture medium. This novel ex vivo NAFLD model could be used to investigate the multicellular and molecular mechanisms that drive NAFLD development and progression, and to study potential anti-steatotic drugs.